Simultaneous determination of tinidazole, furazolidone and diloxanide furoate in a combined tablet preparation by second-derivative spectrophotometry.

A second-derivative spectrophotometric procedure has been developed for the simultaneous determination of tinidazole (TD), furazolidone (FD) and diloxanide furoate (DF) in a commercial preparation. The method consists of the utilization of second-derivative absorption spectra of tablet extract in distilled water and then determination of the analyte concentration in the mixture was carried out using zero-crossing (ZC) and ratio-compensation (RC) techniques. Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of TD (5-20 microg ml(-1)), FD (2.5-10 microg ml(-1)) and DF (7.5-15 microg ml(-1)). The results were found to be accurate and free from interference. The details of the statistical treatment of analytical data are also presented.